"Currently, about 300,000 K-12 students around the country are paying for private schools with public tax dollars, according to the Alliance for School Choice. The group says it wants to double that number," reported Lyndsey Layton of Washington Post.

Sternberg of the foundation told CP that the donations to the Alliance "support their work on a federal and regional level to expand private school choice for families across the country."

"The foundation's investments support ASC efforts to work with parents to identify the best school option for their child, schools to ensure that all options are high-quality and advocates to create and expand more private school choice programs," said Sternberg.

Groups like Americans United for Separation of Church and State have taken issue with the support, with Simon Brown of AUSCS writing that the Walton Family is launching a "war on public education."

"Things haven't worked out real well in Wisconsin, where studies showed students in Milwaukee and Racine (the only districts currently eligible for vouchers), scored lower than their public school peers in both reading and math in 2012," wrote Brown.

"Louisiana's voucher program is a mess too. Some schools there aren't properly tracking the state funds they receive, including a Christian school that used voucher money to pay its sponsoring church for bus and facilities use."